[Impact of an additional inspiration CT scan on the conventional protocol of the ¹⁸F-FDG PET-CT in the detection of small pulmonary nodes]

To determine the impact of an additional inspiration CT scan on the conventional ¹⁸F-FDG PET-CT protocol in the detection of small pulmonary nodules.One hundred consecutive patients who presented with one or various nodules were studied. Whole-body PET-CT was performed using Gemini (Philips). CT acquisition parameters were 120 kV/25 mAs, the same as those for the transmission/fusion CT (mild expiration) and inspiratory CT.A total of 188 nodules were detected in the inspiratory CT with sizes between 0.3-3 cm. Non-inspiratory CT did not show 20/188 nodules (10.6%) with sizes between 0.3-1cm, this corresponding to 17 patients. The most frequent localization of non-detectable nodules in non-inspiratory CT was the lower lobes. ¹⁸F-FDG uptake was detected by the PET in 83.9% and 72% of nodules with1 cm and between 0.7 and 1cm, respectively. However, only 10.5% of nodules0.7 cm showed increased metabolic activity.In selected patients, inspiratory CT added to conventional PET-CT significantly improves the detection of small nodules (10.6%), especially in those lesions located in the lower lobes, due to respiratory movements, and may have an impact on patient management.